Casey Affleck on How Jennifer Garner and Kids Have Inspired Ben to Get Sober (Exclusive)

Family is everything for the Affleck family -- through the good and the bad.

During an interview with ET's Keltie Knight at The Old Man and the Gun press day at Viceroy L'Ermitage in Beverly Hills on Saturday, Casey Affleck opened up about his brother, Ben's, recent return to rehab, and how the Justice League star's kids and ex, Jennifer Garner, have inspired him to get sober.

"Alcoholism has a huge impact on not just the person, but also their family. So, I think for his kids’ sake and for their mom, and for himself, he’s trying to do the work and get it together," Casey explained, noting that he and Ben "come from a long line of alcoholics."

"Ben is an addict and an alcoholic. Most of my grandparents are alcoholics. My father is an alcoholic, as bad as you can be, and he’s been sober for about 30 years. I’ve been sober for about six years," the 43-year-old actor said. "Ben is trying to put it together, and it can be a very hard thing to do. He has the kind of resources and time, luckily, to take the time and go to a good facility."

Ben has been photographed during his outings from rehab lately, and as Casey noted on Saturday, "It can't be easier to have everybody looking at you and taking your picture as you're walking out of an intervention." "I don’t envy that," he added. "I saw my father struggle with it for many years and nobody was following him around with cameras and stuff. It’s not a great look. But on the other hand, it’s nothing to be ashamed of and it’s good that he’s taken care of."

Casey also gave an update on his brother while chatting with ET at the Toronto International Film Festival earlier this week, as he's been hard at work promoting The Old Man and the Gun.

"I think people seemed to like it in the room, it played very well," he told ET on Saturday of the film's TIFF screening. "Overall, it's been received really well, people especially like Robert Redford... They loved the movie."